Flexibility of erythrocytes in juvenile diabetes mellitus

The structural and functional changes of blood cells and molecular components in diabetes mellitus

It is known fact that diabetes mellitus (DM) affects blood cells. Changes in the erythrocyte membrane, disorder in hemoglobin oxygen-binding and modification in mechanical characteristics, are effects of hyperglycemia on red blood cells. Altered susceptibility infection of patients with diabetes has been ascribed to a depression in the function of polymorphonuclear leukocytes. Neutrophil function in patients with diabetes with good glucose control is slightly different than in healthy ones. DM causes significant changes in lymphocytes metabolism and their functions. Patients with diabetes, presenting with acute coronary syndrome, are at higher risk of cardiovascular complications and recurrent ischemic events in comparison to non-diabetic counterparts. Various mechanisms, including endothelial dysfunction, platelet hyperactivity, and abnormalities in coagulation and fibrynolysis have been implicated for this increased atherothrombotic risk. There are many other alterations of blood cells due to DM. In the present review we focused on modifications of blood cells due to DM. Then, as a second point, we explored how the changes affect functions of red blood cells, white blood cells and platelets.

The impact of the HbA1c level of type 2 diabetics on the structure of haemoglobin

This study explores the impact of HbA₁c levels on the structure of haemoglobin (Hb) in patients with type 2 diabetes. Seventy-four diabetic patients were classified into the following two groups based on their level of HbA₁c: group A, patients with good glycaemic control (HbA₁c < 7.0%, n = 36); group B, patients with persistent hyperglycaemia (HbA₁c ≥ 9.0%, n = 38). Thirty-four healthy people served as controls (group H). Hb structure was examined by Fourier transform infrared spectroscopy (FTIR), and diabetic erythrocytes were modelled to estimate the impact of glucose on these cells and Hb. Increasing glucose concentrations altered both erythrocyte parameters and the Hb secondary structure. Group B differed significantly from group H (p < 0.05): in the former, the ordered Hb secondary structure had a strong tendency to transform into a disordered secondary structure, decreasing structural stability. We presumed here that high HbA₁c levels might be a factor contributing to Hb structural modifications in diabetic patients. FTIR spectral analysis can provide a novel way to investigate the pathogenesis of type 2 diabetes mellitus.

Interrelationship of antioxidative status, lipid peroxidation, and lipid profile in insulin-dependent and non-insulin-dependent diabetic patients

This study aimed to investigate the interrelationship of plasma lipid profile, lipid peroxidation, and erythrocyte antioxidative defense in patients with insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes mellitus. Plasma levels of total cholesterol, triglycerides, and lipid peroxides and the activities of copper, zinc superoxide dismutase (CuZnSOD), catalase, glutathione peroxidase (GSH-Px), as well as the amount of glutathione in erythrocytes, were determined in IDDM, NIDDM, and nondiabetic control subjects. Additionally, morphology of erythrocytes in all subjects was examined. Plasma levels of total cholesterol and triglycerides were significantly increased in NIDDM compared with controls. Also, the lipid peroxide level was higher in NIDDM than in either control or IDDM subjects. CuZnSOD activity in erythrocytes was elevated in NIDDM patients compared with the control. In NIDDM patients, more extensive erythrocyte spherocytosis and echinocytosis compared with both control and IDDM subjects were observed. In contrast with the IDDM group, the observed abnormality in lipid metabolism in NIDDM patients is closely associated with increased lipid peroxidation, changes in antioxidative defense, and erythrocyte morphology.

Erythrocyte deformability in diabetes and erythrocyte membrane lipid composition

Erythrocyte deformability was assessed in 40 diabetic patients, 24 insulin-dependent (IDD) and 16 non-insulin-dependent (NIDD), by measuring the initial filtration flow rate of whole blood, isolated red blood cells (RBC), and isolated RBC membranes with the Hanss hemorheometer, and its relationship to the plasma and ghost membrane lipid composition was investigated. RBC deformability was significantly reduced, whereas the deformability of the isolated RBC membranes did not differ significantly from the controls. In the plasma, the triglycerides were high, the high-density lipoprotein (HDL) cholesterol was reduced, and the ratio of total cholesterol over HDL cholesterol was high as compared with the controls. The RBC lipid composition expressed in mumol lipids/10(10) RBC showed significantly lower levels of free cholesterol, sphingomyelines, and phosphatidylcholine, which are the lipids principally located on the outer layer of the RBC membranes. These data suggest that in both IDD and NIDD patients, there may be a relation between these modifications in the RBC lipid composition and rheological impairment of the RBC.

Altered blood rheology in the pathogenesis of diabetic and other neuropathies

Although a substantial literature confirms the abnormal flow properties of diabetic blood, only in a few papers has the vasculitis of diabetic neuropathy been considered to have a hemorheological cause. It is proposed that the pathogenesis of nerve lesions involves an interaction between the specialized nerve vascular system and focal ischemic lesions resulting from rheologically induced stasis. The proposition is extended into other conditions with abnormal blood rheology such as hypothyroidism, uremia, dysglobulinemia, polyarteritis nodosa, and lepromatous leprosy. It is concluded that the treatment of such polyneuropathies should include an agent which would improve the flow properties of the blood.

A reappraisal of the influence of blood rheology on glomerular filtration and its role in the pathogenesis of diabetic nephropathy

The basic assumptions concerning the mechanisms of normal glomerular filtration are discussed. Attention is drawn to blood rheologic changes that follow glomerular filtration and influence postglomerular blood flow adversely. It is proposed that the blood rheologic changes will increase the resistance to flow in the peritubular plexus commensurate with the dimensions of the capillaries and blood viscosity in accordance with the general principles of the Poiseuille formula, even though blood is a non-Newtonian fluid. For this reason, the conditions of flow in the plexus must be a determinant of intraglomerular capillary pressure. When blood rheology is abnormal, as in insulin-dependent diabetic patients, the abnormality will be amplified by glomerular filtration and it is suggested that the consequences will be manifest as problems of blood flow in the peritubular plexus. As the increase in postglomerular intravascular pressure needed to restore the rate of blood flow to normal necessitates dilation of the afferent arteriole and possibly more proximal vessels, such changes will result in an increase in intraglomerular pressure. The increase in pressure that increases filtration is therefore a direct consequence of abnormal blood rheology. This concept provides a basis for understanding the mechanism of diabetic proteinuria and for other proteinurias associated with abnormal blood rheology. A possible role for altered blood rheology in the pathogenesis of both focal and total glomerulosclerosis is discussed, and the potential benefits of agents that improve blood rheology are outlined.

Aggregate formation of erythrocytes and diabetic retinopathy in children, adolescents, and adults with diabetes mellitus (type I)

In vitro measurements were carried out to study the aggregation of erythrocytes in 33 children and young adolescents, three older adolescents, and 38 adults with type I diabetes. The aggregate formation of erythrocytes in stasis was increased in adult patients with both "good" and "poor" metabolic control when compared to control values. The aggregation of red cells in all children and the younger adolescents, both those under good and poor metabolic control, did not statistically differ from those of controls. Each of the three older adolescents showed an increased aggregate formation of their erythrocytes compared to controls. All adult patients under poor metabolic control exhibited various stages of diabetic retinopathy as shown by fluorescence angiography. Only one child under poor metabolic control showed an early stage of retinopathy (stage I according to Malone). The three older adolescents showed an increased aggregate formation of their erythrocytes. These patients exhibited also stage I of retinopathy. We suggest that the increased aggregation of erythrocytes of both adult and older adolescent patients may be one of the reasons for the development of diabetic retinopathy. Moreover, the normal erythrocyte aggregation of the diabetic children and younger adolescents could help to explain the rare occurrence of microangiopathies in childhood diabetes.